This invention relates to tucker folders used in newspaper rotary printing presses.
Tucker folders are known in the art which are provided with picking pins (i.e. needles arranged in line on a base) carried by a folder drum and controlled by a cam. These pins are adapted to hold a printed web on the surface of the folding drum during rotation thereof. The tucker folders are also provided with shafts which are also carried by the folding drum and have tucker blades adapted to initiate a transverse fold on a paper sheet. A pair of folding rollers rotating in opposition is arranged below the folding drum. A space is formed between the folding rollers, the space receiving a folded sheet fed thereinto by the tucker blade, the folded sheet being then delivered from the folder.
To stack the sheets delivered from the folder into piles of newspapers, it is necessary to separate them into separate streams, the newspapers then being subsequently placed into bins by fly-type delivery wheels. The separation of newspapers into streams as described above may be performed with the use of a deflector either mechanically or electrically connected to the folder drum drive.
Though the devices of the kind referred to are reliable in separating the folded newspapers into streams, the deflector is to be switched within a time interval between two successive newspapers, this interval depending on the printing speed. Thus, if the rotational speed of the impression cylinders is about 40,000 rpm, the duration of the above-mentioned interval would be only 0.0225 s.
In view of the present trend in the field of newspaper production to increase the speed of printing, the time interval between successive newspapers is liable to be decreased. This fact may complicate switching of the deflector within such a short interval. This may lead to inadequate utilisation of the printing press capacity.